The United States develops a new type of anti-ballistic missile defence that uses sound waves to deflect incoming warheads, but the system requires a rare mineral that is only available in the Soviet Union. When it is discovered that a sample of the mineral was put aboard the H. M.S. Titanic on her disastrous maiden voyage, a project is hatched, led by Admiral James Sandecker (Jason Robards) to raise the ship from the bottom of the sea. But the Soviets also plan to recover the ship, and agent Dirk Pitt (Richard Jordan) must help in keeping them from doing so.